How effective would a sword be without a hamon?

[piryohae3]

As far as I know the kawagane is high carbon and hard. I wonder if it could maintain a sharp cutting edge whilst being less prone to chipping than a blade that's undergone yaki-ire.

[SAS]

Depends on what you consider sharp, what you are cutting, and for how long.

[Ken-Hawaii]

As Steve points out, you can sharpen a kawagane blade, but it's the shingane addition that turns it into flexible steel. In Japan's early bladesmithing days, hard steel was used to produce swords, but this resulted in countless swords breaking upon impact (https://www.martialartswords.com/blogs/articles/shingane-vs-kawagane-steel-whats-the-difference).

 

As far as the yaki-ire process, are you under the impression that the blade comes out sharp? The edge is actually left somewhere around 1/8" thick during the hardening phase, and after tempering, it's worked down to an actual sharp, thin edge by the togishi.

[Andi B.]

A sword without hamon (means no heat treatment = no hardening) doesn't make any sense. Maybe unhardened kawagane is slightly 'harder' then shingane but it's still too soft.

There is a reason for yaki-ire...

[16k]

Let’s compare with modern Chinese replica. They come in several grade of steel but I think 1060 is probably the best comparison as it is an average hardness. Now, you can get them differentially tempered, so with a Hamon, or through tempered (same hardness everywhere and no Hamon). The latter would be the one closer to a tempered nihonto without Hamon (since I take it for granted they would still be tempered one way or the other. Actually, without Hamon, what we would get is  the equivalent of western broadswords).

 

So what would be the difference? Not that great I think. They would probably absorb shock a little better (since less hard) but they would be a little less sharp and would need more frequent sharpening.

 

...and of course, they’d lose some of their inherent beauty!

[PNSSHOGUN]

Strange concept as full tempering is certainly a known thing for the Japanese sword starting in Meiji with the Murata-To. Anyway, while blade toughness and strength are superior the sharpness and cutting edge are compromised. The edge will dent rather than chip and it won't be able to hold a keen edge for long. In return the swords are "stronger" in terms of not taking a set easily. I have two of these swords from Meiji and Showa and they both have dents in the cutting edge.

[Andi B.]

Hi, while thinking about OP question I ask myself the following:

I assume unhardened low carbon shingane has a similar hardness as unhardened high carbon kawagane. The parts affected by heat treatment are kawagane only, so I wonder, why shingane is used at all...

Has it impact on stability or is it rather used to save on expensive and rare high carbon steel...?

[mas4t0]

It comes down to the metallurgy.

 

In a Nihonto, the hardened steel has greater strength, while iron and sorter steel are more malleable and offer greater toughness.

 

A. Yield strength is a measure of the maximum stress that a material can support before being plastically deformed (bent).

 

B. Tensile strength is a measure of the maximum stress that a material can support before starting to fracture (crack).

 

C. Fracture toughness is a measure of the energy required to fracture a material that contains a crack (snap).

 

If this isn't clear, let me know.

 

All of this can be calculated quantitatively and shown in graphs, it's not qualitative.

 

With traditional steel, you can produce a through hardened blade with superior strength and toughness, though you would have to reduce the harness to achieve this and therefore would have reduced edge holding (consider European style swords).

 

You can improve in all areas (strength, toughness, hardness and edge holding) by using modern steel, but that's a case of superior metallurgy rather then adapting to the material at hand.

 

It's all about the compromises you make.

[ROKUJURO]

  On 1/24/2020 at 1:58 AM, piryohae3 said:

As far as I know the kawagane is high carbon and hard. I wonder if it could maintain a sharp cutting edge whilst being less prone to chipping than a blade that's undergone yaki-ire.

James,

 

you are starting with wrong premises: Not all Japanese sword blades have high carbon KAWAGANE, it depends on the forging technique used. Sharpness is not limited to hard steel, but holding an edge in heavy use is of course better with hardened steel than with low carbon (< 0,22 % C) iron.  

 

If you forge a blade with a soft core and insert a high carbon cutting edge steel (like in HONSANMAI, SHIHOZUME, WARIHA TETSU, or SOSHU KITAE), you do not need to make a differential hardening procedure with clay (TSUCHI OKI). The blade will automatically have a hard edge and a softer body and show a similar feature like a HAMON. . 

 

A flexible body of  a blade is in many cases not the result of the inherent flexibility of the SHINGANE, but of its position between layers of hardened steel. Today, we call this a 'sandwich' type of construction. 

 

In the forging of blades, the smith is always aware of the stress his blade will be submitted to. This is why TANTO mostly have a different inner structure than long blades. Thrusting is a different stress to a piece of metal than slashing with a long blade.

 

I attach an image of a SAN MAI blade with a "HAMON" that was not produced by differential hardening. 

 

[Dave R]

 Traditional Chinese blades are "San Mai" hard steel sandwiched between soft, as are a lot of Eastern blades. Some are edge hardened, some are not, all cut like the very devil.  

 

 Photo of an antique Chinese blade.....

[DoTanuki yokai]

Jean i want to point out that there is no clay or forging style like honsanmai are necessary to produce differentially hardned blades by hadaka-yaki.

This technique is maybe the oldest way to create a hamon, many Ichimonji choji-midare hamon and Aoe saka-choji hamon are thought to have been made using hadaka-yaki.

[Peter Bleed]

Effective? That is complex, but I will say they would not SELL worth a darn...

Peter

[Dave R]

  On 1/24/2020 at 7:44 PM, Peter Bleed said:

Effective? That is complex, but I will say they would not SELL worth a darn...

Peter

 

 Some of us are interested in more than what a sword would sell for. (No offence).

[piryohae3]

  On 1/24/2020 at 11:16 AM, ROKUJURO said:

If you forge a blade with a soft core and insert a high carbon cutting edge steel (like in HONSANMAI, SHIHOZUME, WARIHA TETSU, or SOSHU KITAE), you do not need to make a differential hardening procedure with clay (TSUCHI OKI). The blade will automatically have a hard edge and a softer body and show a similar feature like a HAMON. . 

 

Then I wonder if European swords will also reveal a hamon if given a Japanese style polishing.

[mas4t0]

  On 1/25/2020 at 2:59 AM, piryohae3 said:

Then I wonder if European swords will also reveal a hamon if given a Jappanese style polishing.

There are examples of European swords that show a hamon when polished appropriately.

 

I've seen a German blade from I think the 12th century which showed a hamon.

 

No idea what techniques caused it to manifest in the blade.

[mas4t0]

  On 1/24/2020 at 11:16 AM, ROKUJURO said:

I attach an image of a SAN MAI blade with a "HAMON" that was not produced by differential hardening.

Musterklinge Drei-Lagen 4076.jpg

To be clear, san-mai blades do not show a hamon. They show a line where the unhardened cladding meets the core steel. A hamon specifically delineates between martensite and pearlite microstructures of heat treated steel. A cladding line is simply a delineation between the core of hardened steel and unhardenable iron or stainless steel that has been used as cladding.

 

The core steel (which constitutes the cutting edge) is heat treated exactly the same all the way through from the edge to the spine, while the cladding is unhardenable and does not respond to the heat treatment.

 

It is impossible to show a hamon on a traditional san-mai blade as even with a differential heat treatment, the hamon would be hidden under a layer of unhardenable iron.

 

This is done for a few reasons, but a key one is that soft iron is easier to work after the blade has been heat treated. Many Japanese knives are worked with draw knives to give concavity and convexity to the blade faces.

 

There are traditional Japanese kitchen knives with a hamon. These are monosteel knives, and are differentially hardened.

 

They are only generally recommended for professional use as they are much more brittle and prone to chipping then standard san-mai blades.

 

Some examples:

 

Shigefusa Kasumi (san-mai) Petty

 

Mizuno Suminigashi (san-mai with the cladding layers folded for aesthetics) Gyuto

 

 

Mizuno Honyaki (differentially hardened monosteel) Gyuto

[SAS]

There are a lot of unsupported or overly broad statements here....many nihonto are forged using san mai kitae, and they certainly do have a hamon, produced using differential quenching. Obviously the higher carbon layer is exposed to form the cutting edge, not hidden under a layer of unhardenable iron. Same can be said for many knives.

  On 1/25/2020 at 3:14 AM, mas4t0 said:

To be clear, san-mai blades do not show a hamon. They show a line where the unhardened cladding meets the core steel. A hamon specifically delineates between martensite and pearlite microstructures of heat treated steel. A cladding line is simply a delineation between the core of hardened steel and unhardenable iron or stainless steel that has been used as cladding.

The core steel (which constitutes the cutting edge) is heat treated exactly the same all the way through from the edge to the spine, while the cladding is unhardenable and does not respond to the heat treatment.

It is impossible to show a hamon on a traditional san-mai blade as even with a differential heat treatment, the hamon would be hidden under a layer of unhardenable iron.
 

[mas4t0]

If there's anything specific you take issue with, let me know and I'll clarify.

Are you meaning unhardenable (shigane) cladding, but with a sufficient amount of the hagane exposed to fully show the hamon?

Any examples?

 

  On 1/25/2020 at 5:26 AM, SAS said:

There are a lot of unsupported or overly broad statements here....many nihonto are forged using san mai kitae, and they certainly do have a hamon, produced using differential quenching. Obviously the higher carbon layer is exposed to form the cutting edge, not hidden under a layer of unhardenable iron. Same can be said for many knives.

[SAS]

My answer i think was suficiently clear, but perhaps you need to study a bit more and learn how swords are and were made, and then ask....all swords were and are made with steel of varying carbon contents and will harden to greater or lesser degree. My issue was the misinformation in your comment which i quoted. As a smith I am pretty well informed on the properties of steel and smithing.

[mas4t0]

Steve, san-mai as a lamination style is not one we see in nihonto, honsanmai yes, but not san-mai, it is a technique traditionally used on knives.

 

I don't see what's contentious here, do we have a different understanding of what san-mai means?
 

  On 1/25/2020 at 7:42 AM, SAS said:

My answer i think was suficiently clear, but perhaps you need to study a bit more and learn how swords are and were made, and then ask....all swords were and are made with steel of varying carbon contents and will harden to greater or lesser degree. My issue was the misinformation in your comment which i quoted. As a smith I am pretty well informed on the properties of steel and smithing.

[Ken-Hawaii]

Mark, Steve was using that as an example, not that swords are made that way. If you're less pedantic, you'll get more help.

[mas4t0]

Ken, I don't see what I've said that's pedantic. The comment above was in reference to this, it does seem that Steve was saying that swords are made that way.

 

  On 1/25/2020 at 5:26 AM, SAS said:

There are a lot of unsupported or overly broad statements here....many nihonto are forged using san mai kitae, and they certainly do have a hamon, produced using differential quenching. Obviously the higher carbon layer is exposed to form the cutting edge, not hidden under a layer of unhardenable iron. Same can be said for many knives.

 

Is there disagreement over what is meant by san-mai? Are we referring to the same thing; three layers with hagane in the centre and shigane on either side laminated as shown in the image?

 

[SAS]

There are lots of ways to skin the cat, and also sword blades  Your diagram is certainly one way, but there are many others. San mai or honsanmai can be done in multiple arrangements, and yes, swords are done that way. if you Mark are referring to one specific way in which a knife is made that has high carbon steel in the center of a billet, with iron completely surrounding it, your point would be valid as you stated above, but i do not know what the point of such construction would be, as it is the high carbon steel that when heated above critical and quenched that creates a hard cutting edge that maintains an edge. Whew, that was a long sentence.

[mas4t0]

Thanks Steve. That's all I was trying to express.

 

I didn't realise that people were using 'san-mai' to refer to any other lamination than the one illustrated.

 

Is san-mai being used to refer to anything with 3 layers (irrespective of arrangement) or is it being used as short hand for lamination in general?

 

I was never meaning that the high carbon steel would be completely encased, rather that it was clad by iron.

 

I can see the need to jump in and straighten things out if it read like I was suggesting a kind of inverse kobuse lamination (with the hardened steel serving as the core).

 

I'm glad we straitened that out.

[DoTanuki yokai]

I think people see pictures like this on wikipedia and chinese "katana" dealer sides and take it for real.

I dont think there is any proof that this are common Japanese "lamination" techniques.

[Brian]

By definition, San-Mai is 3 layer construction. I hope Lynn Thompson (Cold Steel) will  keep the lawyers at home.... https://knifenews.com/san-mai-trademark-cold-steel-issues-open-letter-to-the-knife-community/   :rotfl:
 

[Jacques]

  On 1/25/2020 at 11:03 AM, DoTanuki yokai said:

I think people see pictures like this on wikipedia and chinese "katana" dealer sides and take it for real.

I dont think there is any proof that this are common Japanese "lamination" techniques.

 

 

You can exclude Soshu-kitae which was never used by Masamune as often said.

[DoTanuki yokai]

I cant describe how this "soshu"-kitae cringe me :D

[mas4t0]

  On 1/25/2020 at 11:03 AM, DoTanuki yokai said:

I think people see pictures like this on wikipedia and chinese "katana" dealer sides and take it for real.

I dont think there is any proof that this are common Japanese "lamination" techniques.

With regards to the san-mai lamination illustrated above, it is a common Japanese lamination technique, it's the standard for traditionally made double beveled Japanese kitchen knives for one.

 

I believe it's also standard for traditional Japanese axe heads.

[Dave R]

 I have an original and antique Chinese sword in my collection, of San Mai construction. No Hamon, but the edge steel shows as a narrow bright line the thickness of a wire. 

 I bought it about 30 or 40  years ago, when they were cheap. Age unknown, but a bring back from the "Boxer Rebellion".